Core taking apparatus



J. E. HOI- FOSS CORE TAKING APPARATUS Filed June 5, 1958 INVENTOR. VWF/M 'Jo/.m E. Hoffoss.

April 23, 1940.

ATT E'YS.

Patented Apr. 23, 1940 PATENT oE-FlcE conn 'rame APPARATUS John E. lioness, Houston, Tex., assigner to Reed Roller Bit Company, Houston, Tex., a corporation of Texas Application June 3, 1938, Serial No. 211,546

Sclaims.

'I'his invention relates in general to means for obtaining cores of formations through which a hole is being drilled. It has particular reference to a barrel for receiving such a core and to an 6 arrangement for venting the upper end of such barrel.

The general object of this invention is to provide an arrangement for venting the upper end of a core barrel and for preventing down flow 10 into the core barrel without preventing the use v of hydraulic pressure in removing a core from the core barrel.

In drilling wells or other holes particularly in earth formations, it is customary at intervals or continuously to drill the hole in the form of an annulus and to obtain samples of the core within this annulus for the purpose of determiningr the nature and quality of the formation through which the hole is being drilled. This is customarily done by means of a drilling tool known as a core bit, which drilling tool is made hollow and carries cutting devices upon its lower annular edge. The core is adapted to be received within this tool as the drilling proceeds and separate core barrels are customarily located within the core drill for the purpose of receiving the core as it is formed.

In drilling wells and earth formations it is customary to employ a fluid, which for the purpose 80 of this discussion will be referred to as a .drilling mud. This mud is circulated during drilling usually down through the drill stem and up through the open hole for the purpose of washing out the cuttings from the drill and controlling the forma- $5 tion pressures encountered. It is highly desirable that during the drilling operations this drilling mud shall be prevented from washing down through the core barrel. For the purpose of preventing this and yet for venting the core barrel 4g an opening having a check valve therein is customarily provided in the upper end of the core barrel, the check valve being arranged to permit upward flow from the core barrel but to prevent downward ow into the core barrel. 4B In this connection, the core barrel may, de-

pending upon the conditions encountered, be vented to the outside of the drill stem into the up iiowing current of drilling mud or to the inside of the drill stem into the down ow current 50 of the drilling mud. It is also desirable in certain instances that prior to the taking of the core but after the core drill has been lowered into the hole, it may be possible to wash down through the core barrel to clean out any debris which may Il be lodged therein.

Itis desirable also that after a core barrel has been withdrawn from a hole with the core in place therein, the arrangement of parts be such that it is possible to employ hydraulic pressure to force the core out of the core barrel. With the 5 ordinary check valve it is, of course, not possible to wash down through the core barrel after the core barrel has been lowered into the well nor is it possible after the core barrel has been withdrawn with the core in place to employ hydraulic pressure to force the core out of the core barrel without rst removing from the core 'barrel the check valve at the upper end thereof.

It is, therefore, an object of this invention to 15 provide a core barrel with a venting arrangement including means for preventing down ilow into the core barrel during the coring operations, which means will not interfere with the use of hydraulic pressure for removing the core from the core barrel after the core barrel has been 20 withdrawn from a well.

Another object of this invention is to provide a device of the type set forth in which it will be possible after the core barrel has been lowered into the wen to mst wash down through 25 the core barrel to remove debris therefrom before the coring operations ani to then prevent down iiow into the core barrel during the coring operations.

It is an object of this invention t0 provide a 3 device for venting a core barrel either to the exterior or to the interior of a drill stem, while preventing down flow into the core barrel, and

to make possible the removal of the core from the core barrel by hydraulic pressure without necessitating removal from the core barrel of the device for preventing down iiow during the coring operations.

Other objects and advantages of this invention will become apparent from the following de- 40 scription taken in connection with the accompanying drawing wherein is illustrated by way of example one embodiment of this invention.

It is to be understood that thisinvention is to be limited in scope only by the prior art and by the terms of the appended claims.

In the drawing:

Fig. 1 is alongitudinal cross section through the lower end of a drill stem, core drill and core barrel constructed in accordance with this invention and arranged for venting the core barrel to the outside of the drill stem.

Fig. 2 is a view similar to a portion of Fig. 1 but showing the core barrel to be vented to the inside of the drm stem.

Fig. 3 isa view similar to Fig. 2 illustrating the manner of using the apparatus during the washing out of the core barrel prior to the core drilling operations.

Fig. 4 is a longitudinal cross section of the upper end of the core barrel illustrated in Figs. 1 and 2 showing the same and the position of the parts during the removal of a core from the core barrel by means of hydraulic pressure.

Referring now more in detail to the drawing, the construction shown in Fig. 1 includes the lower end of the drill stem I, to which is secured l a special sub 2 the purpose of which will be explained presently. On the lower end of this sub is mounted a special coupling 3 and Ithreaded into the lower end of this coupling is the outer core barrel 4. A special sub is provided at 5 secured to the lower end of the outer core barrel 4 and threaded at its lower end to receive the core drill 6. This core drill may be of any conventional construction but is illustrated as having lower cutters 'I and 8 at its lower end and having an inner recess just above its lower end for the purpose of receiving the core catcher structure generally designated by the numeral 9.

For the purpose of protecting the core catcher structure just referred to, there is provided a sleeve like member I which is placed in the lower end of the bit and adapted to extend past the core catcher structure during the lowering of the core bit into the well. This sleeve I0 is longitudinally slit along its lower portion as shown at I I and is provided with external lugs I2 intermediate the slits Il which lugs normally prevent the sleeve from moving upwardly into the core barrel. The sleeve is held against downward movement by engagement of the core catcher finger I3 in notches I4 in the exterior surface of the sleeve.

Within the outer core barrel 4 is mounted the inner core barrel I5 which will -hereinafter be referred to as the core barrel, the element 4 being designated as the outer core barrel, for the purpose of distinguishing it from the element I5. To the lower end of the core barrel I5 is threadedly secured an element I6 of substantially the same inner diameter as the core barrel but having a part at its lower end fitting over the upper part of. the core catcher structure and seating at I1 within a core bit 6. At its upper end the core barrel I6 is internally threaded to receive a head I8. This head I8 is provided with a passageway therethrough threaded at its lower end I9 and at its upper end and provided with an enlarged central portion 2I. Into the lower threaded portion I9 is secured a retaining nut 22 which in turn holds a valve seat element 23 in position. This valve seat element as illustrated presents an upwardly facing valve seat substantially at the lower portion of the chamber 2|. Into the upper threaded end 20 of the head I8 there is threaded as illustrated in Fig. 1 a venting tube or nipple 24. This tube or nipple is surrounded by packing rings 25 or the like and fits within a downwardly extending tubular part 26, on the lower end of the sub 2. 'I'his downwardly extending part 26 is hollow and at the upper end of the hollow section there is provided laterally extending openings 21 communicating with the exterior of the sub. It will thus be seen that a venting passage is provided from the barrel l5 through the head I8, the venting tube 26 and the passage 2'I in the sub 2 to the exterior of the drill stem.

For the purpose of conveying the slush or drilling mud from the interior of the drillstem to the bit the sub 2 is provided with passageways 2l extending longitudinally thereof and emptying into the space around the tubular extension 26. The head I8 is provided with external longitudinal ribs 28 between which the drilling mud may flow. These ribs maintain the core barrel I5 in a centered position and provide an annular passage around the core barrel for the drilling mud. The fitting I6 is likewise provided with external ribs 30 between which the drilling mud passes to the slush passageways 3l in the bit 6.

During the coring. operations with the Yapparatus shown in Fig. 1, the core bit is first lowered into the well with the sleeve III projecting from the lower end thereof, until this lower end strikes the bottom of the hole. When this occurs, the parts between the slits II in this sleeve will be sprung inwardly so as to permit the lugs I2 to pass upwardly into the core barrel. Then as drilling proceeds an annular cut will be made and the core will force the sleeve I0 `into the core barrel.

During this coring operation the slush or drilling mud which is in the core barrel will be forced outwardly through the passageway in the head I8 through the tubular venting element 24 and the passageways 2l to the exterior of the drill stem. Any flow downwardly into the core barrel will be prevented by means of a ball valve 32 located in the chamber 2| and permitted to seat against the valve seat 23. During the coring operation the core barrel is free to rotate and any upward thrust against the core barrel will be taken by the bearing ring 33 which is preferably made of rubber or the like. In this connection it has been found that a ring of rubber in the presence of the drilling iiuid employedforms an excellent bearing for the upper end of the core barrel.

Referring now to Fig. 2 of the drawing, it is to be noted that the sub 2 has been in this figure eliminated and the drill stem I is threaded directly to the collar 3. In this form also the rubber bearing ring 33 has been removed from the core barrel head I8 and the cage 34 having lateral openings 35 therein has been threaded into the upper end oi the head I8 in a position to surround the venting tube 24 without being in contact with this venting tube.

Adjacent its upper end, the cage 34 is provided with an external upwardly facing shoulder 36 and just above this shoulder. the lower end of the drill stem is provided with a downwardly facing shoulder 31. Between these shoulders is interposed a bearing ring 38 which, like the ring 33 isv preferably made of rubber and serves to take the thrusts from the core barrel. In the set-up illustrated in Fig. 2, A.the operation is similar to that shown in Fig.;- 1 with the exception that the slush or drilling uid from within the core barrel first passes the valve 32 and then flows through the venting tube 24 through the down flowing stream of drilling fluid from the drill stem. 'Ihis drilling uid from the drill stem passes between the venting tube 24 and the upper end of the cage 34 vand thence outwardly through the openings 25 in the cage 34 and down around the outside of the core barrel I 5 as in the previous instance.

In Fig. 3 the device illustrated is identical with that shown in Fig. 2 except that the venting tube in Fig. 2 has been omitted so that the ball valve may be left out of the set-up after it is llowered into the well. Fluid may then be pumped downwardly into the drill stem and the core barrel for the purpose of washing out and removing any debris which may have become lodged therein during the lowering of the drill stem. After this washing out operation, the ball valve 32 is then dropped into the lower end of the drill stem and forced downwardly until it passes into the head I8 and seats against the valve seat 23, as in the previously desc-ribed arrangements. The operation of the device illustrated in Fig. 3, except as already stated, is exactly the same as that shown in Fig. 2, the fluid flowing from the core barrel instead of passing through the tubular venting pipe 24, passing directly into the cage 34.

In the case of all of the foregoing devices, when the core barrel is withdrawn from the well with a core in place therein, it has been found that the most expeditious way of removing the core from the core barrel is to apply a hydraulic pressure within the upper end of the core barrel thus forcing the core out at the lower end of the core barrel. When a check valve is used in the upper end of a core barrel, it is, of course, impossible to apply a hydraulic pressure within the upper end of the core barrel without first removing this check valve. In the case of the present construction, however, the removal of the check valve is unnecessary. All that is necessary is that the core barrel be placed in a horizontal position before the hydraulic pressure is applied. When placed in the horizontal position, the ball valve 32 will move laterally within the chamber 2| and take up a position such as illus-7 trated in Fig. 4. When this valve is in the position shown, it is quite clear that it will not interfere with the application of hydraulic pressure to the interior of the core barrel. The passageway through the venting tube 24 and past the valve seat 23 will be perfectly clear and even though a considerable flow of fluid under pressure might be induced through the head I8, this flow will not serve to seat the valve 32 because the valve 32 will be held by gravity in a position within the vchamber 2l spaced laterally from the direct path of the fluid flow into the core barrel.

It will be seen from the foregoing that there has by this invention been provided a device in which a core barrel may be vented either to the exterior or to the interior of a drill stem as desired and in which it is possible to after lowering a drill stem into a well, rst pump down through the core barrel to wash it out and then insert a check valve for preventing down ow into the core barrel during the coring operations. At the same time it will be seen that there has been provided an eflicient thrust bearing for the upper end of the core barrel.

It will be particularly noted that there has been provided by this invention a means whereby all of the foregoing results may be accomplished and whereby at the same time, it will be possible once the core barrelhas been withdrawn from the well to utilize hydraulic pressure for removing the core therefrom without the necessity for first removing the check valve located at the upper end of the core barrel.

Having described my invention, I claim:

l. In a core barrel having an opening at its upper end, an upwardly facing valve seat in said opening intermediate its ends, an enlargement above said valve seat and a valve element adapted to seat against said seat, said enlargement being of such extent in every direction from the axis of said opening as to receive a major portion of said valve, whereby when said core barrel is in vertical position, said valve will permit flow from said core barrel and prevent flow into said core barrel, and when said core barrel is in horizontal position said valve will occupy an inactive positon inside said enlargement and flow may freely take placeboth into and from said core barrel.

2. In combination, in a core barrel having a passageway through its upper end, means for preventing flow therethrough into said core barrel and permitting flow therethrough out of said core barrel when said core barrel is in substantialy vertical position, and means for retaining said last mentioned means out of active position when it is desired to cause flow into said core barrel through said passageway.

3. In combination, a core bit, a drill stem extending upwardly therefrom, a core barrel within said bit and said drill stem having a passageway through its upper end and a cage on its ,upper end providing an external upwardly facing houlder, a part in said drill stem providing an in ernal downwardly facing shoulder overlying said shoulder on the core barrel and a rubber-like bearing ring interposed between said shoulders. i

4. In combination, a core bit, a drill stem extending upwardly therefrom, a core barrel therein having a passageway through its upper end, means for preventing down flow through said passageway into said core barrel and permitting up flow therethrough out of said core barrel when said barrel is in substantially vertical position, and means for retaining said last mentioned means out of active position when it is desired to cause ow into said core barrel through said passageway, the passageway through the upper end of said core barrel being in communication with the exterior of said drill stem when said core barrel is located in said drill stem.

5. In combination, a core bit, a drill stem extending upwardly therefrom, a core barrel therein having a passageway through its upper end. means for preventing down ow through said passageway into said core barrel and permitting up flow therethrough out of said core barrel when said barrel is in substantially vertical position, and means for retaining said last mentioned means out of active position when it is desired to cause flow into said core barrel through said passageway, the passageway at the upper end of said core barrel opening into said drill stem.

JOHN E. HOFFOSS'. 

